RHEL7: Soft lockup occurs in NFS client on mount

Issue

• Soft lockup occurs with following logs:

Oct 29 14:01:44 localhost kernel: NMI watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [mount.nfs:437322]
Oct 29 14:01:44 localhost kernel: CPU: 5 PID: 437322 Comm: mount.nfs Kdump: loaded Tainted: G             L ------------ T 3.10.0-1062.4.1.el7.x86_64 #1
Oct 29 14:01:44 localhost kernel: Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Oct 29 14:01:44 localhost kernel: RIP: 0010:[<ffffffff99981125>]  [<ffffffff99981125>] _raw_spin_unlock_irqrestore+0x15/0x20
Oct 29 14:01:44 localhost kernel: Call Trace:
Oct 29 14:01:44 localhost kernel: [<ffffffff992c5ef6>] finish_wait+0x56/0x70
Oct 29 14:01:44 localhost kernel: [<ffffffffc09694a1>] nfs_wait_client_init_complete+0xa1/0xe0 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffff992c62a0>] ? wake_up_atomic_t+0x30/0x30
Oct 29 14:01:44 localhost kernel: [<ffffffffc096ae9b>] nfs_get_client+0x22b/0x470 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0a7251c>] nfs4_set_client+0x9c/0x150 [nfsv4]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0a73cce>] nfs4_create_server+0x13e/0x3b0 [nfsv4]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0a6ac9e>] nfs4_remote_mount+0x2e/0x60 [nfsv4]
Oct 29 14:01:44 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:01:44 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:01:44 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:01:44 localhost kernel: [<ffffffffc0a6abc6>] nfs_do_root_mount+0x86/0xc0 [nfsv4]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0a6afc4>] nfs4_try_mount+0x44/0xc0 [nfsv4]
Oct 29 14:01:44 localhost kernel: [<ffffffffc096b6d7>] ? get_nfs_version+0x27/0x90 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0977d9b>] nfs_fs_mount+0x4cb/0xdc0 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0978d00>] ? nfs_clone_super+0x140/0x140 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffffc0976bb0>] ? param_set_portnr+0x70/0x70 [nfs]
Oct 29 14:01:44 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:01:44 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:01:44 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:01:44 localhost kernel: [<ffffffff9946e37f>] do_mount+0x1ef/0xce0
Oct 29 14:01:44 localhost kernel: [<ffffffff99445aaa>] ? __check_object_size+0x1ca/0x250
Oct 29 14:01:44 localhost kernel: [<ffffffff9942381c>] ? kmem_cache_alloc_trace+0x3c/0x200
Oct 29 14:01:44 localhost kernel: [<ffffffff9946f1b3>] SyS_mount+0x83/0xd0
Oct 29 14:01:44 localhost kernel: [<ffffffff9998bede>] system_call_fastpath+0x25/0x2a

Oct 29 14:02:16 localhost kernel: NMI watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [mount.nfs:437322]
Oct 29 14:02:16 localhost kernel: CPU: 5 PID: 437322 Comm: mount.nfs Kdump: loaded Tainted: G             L ------------ T 3.10.0-1062.4.1.el7.x86_64 #1
Oct 29 14:02:16 localhost kernel: Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Oct 29 14:02:16 localhost kernel: RIP: 0010:[<ffffffffc096ae89>]  [<ffffffffc096ae89>] nfs_get_client+0x219/0x470 [nfs]
Oct 29 14:02:16 localhost kernel: Call Trace:
Oct 29 14:02:16 localhost kernel: [<ffffffffc0a7251c>] nfs4_set_client+0x9c/0x150 [nfsv4]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0a73cce>] nfs4_create_server+0x13e/0x3b0 [nfsv4]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0a6ac9e>] nfs4_remote_mount+0x2e/0x60 [nfsv4]
Oct 29 14:02:16 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:02:16 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:02:16 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:02:16 localhost kernel: [<ffffffffc0a6abc6>] nfs_do_root_mount+0x86/0xc0 [nfsv4]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0a6afc4>] nfs4_try_mount+0x44/0xc0 [nfsv4]
Oct 29 14:02:16 localhost kernel: [<ffffffffc096b6d7>] ? get_nfs_version+0x27/0x90 [nfs]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0977d9b>] nfs_fs_mount+0x4cb/0xdc0 [nfs]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0978d00>] ? nfs_clone_super+0x140/0x140 [nfs]
Oct 29 14:02:16 localhost kernel: [<ffffffffc0976bb0>] ? param_set_portnr+0x70/0x70 [nfs]
Oct 29 14:02:16 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:02:16 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:02:16 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:02:16 localhost kernel: [<ffffffff9946e37f>] do_mount+0x1ef/0xce0
Oct 29 14:02:16 localhost kernel: [<ffffffff99445aaa>] ? __check_object_size+0x1ca/0x250
Oct 29 14:02:16 localhost kernel: [<ffffffff9942381c>] ? kmem_cache_alloc_trace+0x3c/0x200
Oct 29 14:02:16 localhost kernel: [<ffffffff9946f1b3>] SyS_mount+0x83/0xd0
Oct 29 14:02:16 localhost kernel: [<ffffffff9998bede>] system_call_fastpath+0x25/0x2a

Oct 29 14:02:44 localhost kernel: NMI watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [mount.nfs:437322]
Oct 29 14:02:44 localhost kernel: CPU: 5 PID: 437322 Comm: mount.nfs Kdump: loaded Tainted: G             L ------------ T 3.10.0-1062.4.1.el7.x86_64 #1
Oct 29 14:02:44 localhost kernel: Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Oct 29 14:02:44 localhost kernel: RIP: 0010:[<ffffffff9957ffbc>]  [<ffffffff9957ffbc>] _atomic_dec_and_lock+0x1c/0x70
Oct 29 14:02:44 localhost kernel: Call Trace:
Oct 29 14:02:44 localhost kernel: [<ffffffff992c62a0>] ? wake_up_atomic_t+0x30/0x30
Oct 29 14:02:44 localhost kernel: [<ffffffffc096a1aa>] nfs_put_client+0x6a/0x140 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffffc096aea3>] nfs_get_client+0x233/0x470 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0a7251c>] nfs4_set_client+0x9c/0x150 [nfsv4]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0a73cce>] nfs4_create_server+0x13e/0x3b0 [nfsv4]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0a6ac9e>] nfs4_remote_mount+0x2e/0x60 [nfsv4]
Oct 29 14:02:44 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:02:44 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:02:44 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:02:44 localhost kernel: [<ffffffffc0a6abc6>] nfs_do_root_mount+0x86/0xc0 [nfsv4]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0a6afc4>] nfs4_try_mount+0x44/0xc0 [nfsv4]
Oct 29 14:02:44 localhost kernel: [<ffffffffc096b6d7>] ? get_nfs_version+0x27/0x90 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0977d9b>] nfs_fs_mount+0x4cb/0xdc0 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0978d00>] ? nfs_clone_super+0x140/0x140 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffffc0976bb0>] ? param_set_portnr+0x70/0x70 [nfs]
Oct 29 14:02:44 localhost kernel: [<ffffffff9944da8e>] mount_fs+0x3e/0x1b0
Oct 29 14:02:44 localhost kernel: [<ffffffff993e15f5>] ? __alloc_percpu+0x15/0x20
Oct 29 14:02:44 localhost kernel: [<ffffffff9946bc27>] vfs_kern_mount+0x67/0x110
Oct 29 14:02:44 localhost kernel: [<ffffffff9946e37f>] do_mount+0x1ef/0xce0
Oct 29 14:02:44 localhost kernel: [<ffffffff99445aaa>] ? __check_object_size+0x1ca/0x250
Oct 29 14:02:44 localhost kernel: [<ffffffff9942381c>] ? kmem_cache_alloc_trace+0x3c/0x200
Oct 29 14:02:44 localhost kernel: [<ffffffff9946f1b3>] SyS_mount+0x83/0xd0
Oct 29 14:02:44 localhost kernel: [<ffffffff9998bede>] system_call_fastpath+0x25/0x2a